Streams As part of the course work, a class at an upstate NY college collects data on streams each year. Students record a number of biological, chemical, and physical variables, including the stream name, the substrate of the stream (limestone, shale, or mixed), the pH, the temperature (C), and the BCI, a measure of biological diversity. a) Name each variable, indicating whether it is categorical or quantitative, and giving the units if available. b) These streams have been classified according to their substratethe composition of soil and rock over which they flowas summarized in the table. What kind of graph might be used to display these data?
Stat 461: Week 1 Notes Principles of Experimental Design 1. What is being assumed 2. Nuisance/Noise Factors (aka Confounding Variables) a. Def: factors other than one being studied which could alter the experiment (ex: if you’re seeing what type of fertilizer is best for a crop confound variables could be the soil; if two crops have two different soil types and two different fertilizer types the crop yield may be larger/smaller due to the soil and not the fertilizer) b. Statistical Model- the difference between the mean of the data and one piece of data is due to confounding variables ( = + = mean plus confounding